Deterioration and Optimal Rehabilitation Modelling for Urban Water Distribution Systems

Pipe failures in water distribution systems can have a serious impact and hence it’s important to maintain the condition and integrity of the distribution system. This book presents a whole-life cost optimisation model for the rehabilitation of water distribution systems. It combines a pipe breakage number prediction model with a pipe criticality assessment model, which enables the creation of a well-constructed and more tightly constrained optimisation model. The pipe breakage number prediction model combines information on the physical characteristics of the pipes with historical information on breakage and failure rates. A weighted multiple nonlinear regression analysis is applied to describe the condition of different pipe groups. The criticality assessment model combines a pipe’s condition with its hydraulic significance through a modified TOPSIS. This model enables the optimisation to focus its efforts on those important pipes. The whole life cost optimal rehabilitation model is a multiple-objective and multiple-stage model, which provides a suite of rehabilitation decisions that minimise the whole life cost while maximising its long-term performance. The optimisation model is solved using a modified NSGA-II. The utility of the developed models is that it allows decision makers to prioritize their rehabilitation strategy in a proactive and cost-effective manner.

1 Introduction 1.1 Background 1.2 Pipe Deterioration, Failure and Rehabilitation 1.3 Research Contents and Technical Roadmap 2 Water Distribution System Rehabilitation Strategy and Model 2.1 Introduction 2.2 Pipe Deterioration Models 2.3 Pipe Criticality Assessment Model 2.4 Water Main Optimal Rehabilitation Decision Model 2.5 Summary 3 Pipe Breakage Number Prediction Model 3.1 Introduction 3.2 Pipe Deterioration Influence Factor 3.3 Methodologies 3.4 Modelling 3.5 Summary 4 Pipe Criticality Assessment Model 4.1 Introduction 4.2 Indicators Concerning Criticality 4.3 Methodology for Pipe Criticality Assessment 4.4 Disadvantage and Modification of TOPSIS4.5 Summary 5 Optimal Rehabilitation Decision Model 5.1 Introduction 5.2 General Optimization Design and Rehabilitation Model Review 5.3 Multiple Motivations of WDS Rehabilitation 5.4 Elements of Modelling 5.5 Objectives and Constraints in Different Stages 5.6 Optimization Algorithm for Present Stage Decision 5.7 Optimization Algorithm for Future Stages Decision 5.8 Discussion 5.9 Summary 6 Case Study 6.1 Introduction 6.2 Case Study of Pipe Breakage Number Prediction Model 6.3 Case Study of Pipe Criticality Assessment Model 6.4 Case Study of Water Main Optimal Rehabilitation Decision Model 6.5 Summary 7 Summary, Conclusions and Recommendations 7.1 Introduction 7.2 Pipe Breakage Number Prediction Model 7.3 Pipe Criticality Assessment Model 7.4 Water Main Optimal Rehabilitation Decision Model 7.5 Recommendation of Future Work References

Yi Zhou is a member of the faculty in Wuhan University, China. His main interests are water distribution systems, urban sewerage, drainage and flood control systems.